In the past two years, we have developed a comprehensive project to reduce the risk of nosocomial urinary tract infections in hospitalized patients who receive indwelling urethral catheters. We have completed a prospective study to define risk factors associated with these infections, established continuing daily bacteriologic monitoring of urinary drainage systems by a catheter team, developed a system for incorporating our bacteriologic and epidemiologic data into patients' computerized hospital records, completed a double-blind controlled study to evaluate the effectiveness of systemic antibiotics in catheterized patients, and begun controlled studies to evaluate newer methods for the prevention and control of these infections. We will evaluate our daily bacteriologic monitoring system as a technique to assist in patient care, medical audit, and long-term epidemiologic study. In addition, we will define the clinical importance of catheter-induced infections by determining the incidence of gram-negative rod bacteremia attributable to catheter-associated bacteriuria, and by evaluating host and iatrogenic factors which influence susceptibility to bacteremia. As part of our evaluation, we will implement and test practical methods of prevention and control in our own and affiliated hospitals. With our computer-based system, we are now able to collect, store, retrieve, and analyze the large volumes of data required for these epidemiologic studies. We anticipate that this system of intensive surveillance may serve as a model for the study and control of other nosocomial infection problems.